Apparatus for processing raw organic material into clean, sterilized powder, meal or flakes

ABSTRACT

An apparatus and process are provided for rapidly and efficiently processing raw organic material into high quality clean, sterilized powder, meal or flakes. Means are provided for dividing the organic material into particles of substantially uniform size and for feeding the particles into milling and heating means. The particles are then simultaneously milled and heated by applying centrifugal forces and substantially equal and opposed aerodynamic forces to the particles until the desired powder, meal or flakes are produced. The powder, meal or flakes are then withdrawn from the milling and heating means and heated air and steam are separated therefrom.

United States Patent 9 Schwey et al.

[111 3,761,024 1 1 Sept. 25,1973

[ 1 APPARATUS FOR PROCESSING RAW 3,401,801 9/1968 Wedemeyer et a1 210/394 ORGANIC MATERIAL INTO CLEAN 1,783,358 12/1930 Crites et a1. 241/33 1,814,560 7/1931 Kreisingerm... STERIUZED POWDER MEAL 0R FLAKES 2,152,367 3/1939 Smith 241/33 x [76] Inventors: Joseph ,I. Schwey; Polly E. Schwey, 2,450,522 10/1948 North 210/394 X b h f 1953 33 Ave; Joseph L 3,078,048 2/1963 Russell et aL... 241/33 X p i 815 Ln n of Vero 3,276,353 10/1966 Burner et a1 241/33 X Beach, Fla. 32960 I Y 1 Primary Examiner-Granvi 1e Custer, Jr. [22] Filed: June 30, 1971 Atwmey Finnegan et aL [21] Appl. No.: 158,497

Related us. Application Data [57] ABSTRACT [63] continuatiomimpan of Ser 98,005, Dec- 14 An apparatus and process are provided for rapidly and 1970, abandoned efficiently processing raw organic'material into high quality clean, sterilized powder, meal or flakes. Means [52] us. Cl 241/23, 241/34, 241/54, are Provided for dividing the Organic material into p 2 1 5 241 791 ticles of substantially uniform size and for feeding the 511 int. Cl. 1102c 18/40 Particles into milling and heating means The particles 58 Field of Search 241/33, 34, 36, 47, are then Simultaneouslymilled and heated by pp y 241/54 57 3 ,5 1 3 791 23 27; centrifugal forces and substantially equal and opposed 0 393 39 aerodynamic forces to the particles until the desired powder, meal or flakes are produced. The powder, 5 References Cited meal or flakes are then withdrawn from the milling and UNITED STATES PATENTS heating means and heated air and steam are separated therefrom. 2,704,257 3/1955 Sollano et al. 241/34 X 882,256 3/1908 Lee 210/394 X 14 Claims, 7 Drawing Figures FEED HOPPER l 2 FEED SPEED PRESZSJTTEH MOT? OGJTROLLER l RETERING SCR I B a) 1 l 26 26 1 V 1 F a l DEHYDRATOR I G 21\ SPEED TEMPERATURE CONTROLLER L /lfi CONTRO.

MOTOR RAW MATERIAL RAW MATERIAL r 5 if SHEU 2 0F 4 PAIENIEDSEP25I9I3 I HEATED AIR PAIENTEDSEPZSIHB SHEU 3 0F 4 ATTORNEYS PAIENIEDSEPZBIBH 3.761.024

SHEU I; (If 4 INVENTORS JOSEPH J. SCHWEY POLLY E. SCHWEY JOSEPH L. POGGIE Fa /262a, /ma ezson .& 7210600) ATTORNEYS APPARATUS FOR PROCESSING RAW ORGANIC MATERIAL INTO CLEAN, STERILIZED POWDER, MEAL OR FLAKES This application is a continuation-in-part of application Ser. No. 98,005, filed Dec. 14, 1970, for Improvements in Mill Dehydrators now abandoned.

This invention relates to a process and apparatus for rapidly and efficiently processing raw organic material into clean, sterilized powder, meal or flakes. more particularly, this invention relates to a process and apparatus for processing all types of organic material (including waste material) into clean, dry, sterilized powder, meal, or flakes that are suitable for use as a fertilizer, food for humans, animals, fish or fowl and foruse as a starting product from which various types of pharmacological and medicinal products can be produced.

By use of this apparatus and process, organic waste material can be returned to the ecological system, and ground, water and air pollution can be prevented while an increased supply of food can be provided.

The powder, meal, or flakes produced by the process and apparatus of this invention are also unique. The product produced by the apparatus is characterized by a greatly reduced bacteria count when compared to products produced by previously known milldehydrator machines and processes. This is due, in part, to the short time period required to heat the mate rial when compared to the far longer time period required in prior art devices. These longer time periods may sometimes actually encourage bacteria growth.

In addition, where prune pits, for example, are used as an input to the apparatus, hydrocyanic acid is withdrawn by the process and the end product produced is of such quality and quantity that it has significant value in the preparation of various medicinal products.

The present state of the art for mill-dehydrators is limited to two basic concepts. The most commonly used arrangement comprises a long tube that is heated and rotated simultaneously. The raw material is introduced at one end and is heated and ground while it travels the length of the tube. The material ultimately emerges from the opposite end as a roughly ground powder. This rough powder is then ground to the desired size in a conventional hammer mill.

The second most commonly used process first grinds the raw material to medium sized pieces. These medium sized pieces are then heated and ground to a pulp, and the pulp is finally mixed with hot air to reduce it to a powder.

These prior art machines and processes have been of some value but have not proved entirely satisfactory for many reasons. For example, each requires that the material be pre-cooked and pressed to remove excess water and oil. This pre-cooking and pressing destroys many of the vital elements in the material because of exposure of the material to heat for a relatively long period of time. In addition, the prior art devices are extremely large and expensive and are very costly to maintain and operate. The length of time required to process (the raw material to the finished) product is also substantial so that the yield of the finished product per unit time from these prior art devices is relatively small.

In the most commonly used prior art device, wherein along tube is utilized, the destruction of the vital elements in the raw material is brought about because the rotating tube or drum contains pieces of material ranging in size from large chunks of raw material'to small grains of finished dry material. As a result, the raw material presents a wide range of volume-area ratios so that it is impossible to provide optimum drying conditions. The heat adsorption rate of the large pieces is limited by the low area-volume ration, and the small particles are rapidly dried because: of their high are volume ratio.

The heat transfer rate to the larger pieces can only be increased by increasing the temperature of the air and- /or drum surface or by raising the heat transfer coefficient by increasing the air velocity.

Unfortunately, if the air temperatures are elevated, the small particles are burned and the exposed areas of the large pieces are also burned. Burning, of course, is

undesirable and destroys the vital elements sought to be retained in the finished product. Similarly, increasing the heat transfer co-efficient by increasing the air velocity requires that the air volume also be increased with attendant loss of efficiency. Even with conditions at the optimum obtainable with this long rotating tube arrangement, experience has shown that the processing time for most material is several hours. This long processing time results in the destruction of heat-sensitive protein, vitamins and nitrates in addition to general burning of the material and may often actually encourage bacteria growth.

The second most commonly used prior art method is a partially successfully attempt to overcome the objectional features of the rotating drum arrangement. By separating the grinding and drying operations, charring is largely eliminated; however, the heat transfer rate is low because the air velocity relative to the material is extremely low even though the absolute velocity of the heated air is high. The net result is that the machine is very large, the processing time is long, and the heatsensitive protein is destroyed because of the long time exposure to heat. The efficiency of this method is also extremely low.

It is, therefore, an object of the present invention to provide apparatus for optimizing the drying and grinding process for coverting raw organic material into clean, dry, sterilized powder, meal or flakes.

Another object is to provide a process and apparatus for processing raw organic material while preventing deterioration of vital elements in the material.

A further object of the invention is the provision of a process and apparatus for processing raw organic material in a single, high speed operation.

Still another object is to provide apparatus for processing raw organic material into clean, dry, sterilized powder high in protein, low in ash, high in digestibility, and low in bacteria, count.

Yet another object is to provide apparatus for very quickly and efficiently processing raw organic material into clean, sterilized powder, meal or flake.

Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages are realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

To achieve these and other objects, the present invention provides means, which as embodied and broadly described, comprise feed means for metering organic material and for dividing the material into par ticles of substantially uniform size; means located for receiving organic material from the feed means and for simultaneously milling and heating the organic material by applying centrifugal forces and substantially equal and opposed aerodynamic forces to the material until the desired powder, meal or flakes are produced and the aerodynamic forces become greater than the centrifugal forces; means in fluid communication with the milling and heating means for enabling powder, meal or flakes to be withdrawn from the milling and heating means; and means in fluid communication with the withdrawing means for separating the powder, meal or flakes from heated air and steam exiting from the withdrawing means.

Preferably, the milling and heating means include a furnace having an interior portion in fluid communication with the heating and milling means for enabling heated air to pass from the interior of the furnace into the milling and heating means to heat organic material within the milling and heating means. Additionally, it is preferred that the apparatus include control means connected for sensing the temperature of air, steam, and the powder, meal or flakes exiting from the withdrawing means and for controlling operation of the feed means and of the furnace.

The milling and heating means preferably comprises a housing having a first inlet for receiving heated air, a second inlet for receiving organic material from the feed means and an outlet for exhausting powder, meal, or flakes from the housing; a shaft positioned within the housing for rotation about its own axis; means coupled to the shaft for rotating the shaft about its own axis; and a plurality of instruments; such as knives or hammers, fastened to the shaft for acting upon organic material within the housing in the presence of heated air from the furnace to produce powder, meal or flakes within the milling and heating means. It is also preferable that the milling and heating means be constructed so that the outlet of the housing forms an annular opening around one end of the shaft and wherein the second inlet of the housing is located adjacent to the opposite end of the shaft. The first outlet of the housing is also positioned to permit heated air to enter the interior of the housing radially with respect to the shaft to permit the desired balancing of centrifugal and aerodynamic forces on the material particles within the housing.

Thus, this invention provides for a high efficient process and apparatus for processing raw organic material into clean, dry, sterilized powder, meal or flakes in an extremely short period of time.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention.

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate one embodiment of the invention, and together with the description, serve to explain the principles of the invention.

IN THE DRAWINGS:

FIG. 1 is a block diagram view showing the apparatus of this invention;

FIG. 2 is a diagrammatic plan view of the milling and heating means of the invention;

FIG. 3 is a diagrammatic vertical elevation view of the milling and heating means;

FIG. 4 is a diagrammatic vertical cross section view of the fumace;

FIG. 5 is a diagrammatic illustration of one embodiment of the burner means of the invention;

FIG. 6 is a diagrammatic view of another burner means arrangement; and

FIG. 7 is a diagrammatic illustration of a portion of the feed means for separating solids from fluids.

The apparatus and process of this invention initially pre-processes the raw organic material before milling and heating. This is done automatically and includes cutting the raw material such as fish heads, crab shells, shrimp shells, chicken waste, hyacinths, etc. into relatively small and substantially uniformly sized pieces, heating the raw organic material just enough to break down the fatty tissue and then pressing it, if necessary as with fish, to remove excess oil and water.

After the pre-processed material enters the milling and heating means or the mill dehydrator, all of the particles are within a predetermined size range and no extremes in area-volume ratios exist. The ratio of mechanical energy (grinding) to heat energy (drying) in the mill dehydrator is optimized in the process of this invention. The grinding and drying are also accomplished simultaneously and are completed within only a few seconds as compared to presently known processes which require as many as several hours to produce a similar product.

High speed hammers and/or blades in the mill dehydrator; in addition to supplying high mechanical energy for grinding the material in a small space, provide high centrifugal forces to the material in opposition to a high velocity hot air stream that enters the mill. This results in a very high relative velocity between the material and the heated air and a high heat transfer coefficient between the air and the material being processed. In addition, because the mill dehydrator of this invention is of a small size, the mill allows the use of high velocity air but does not require high volumetric flow.

The apparatus of this invention provides a high speed process, and the apparatus is lightweight, compact, inexpensive, efficient, easily maintained and requires a minimum of operating crew. The apparatus also provides an end product that is extremely uniform in size and moisture content and which has no harmful bacterla.

With reference now to the drawings, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in FIG. 1 a feed hopper 1 for receiving the raw material. In accordance with the invention, feed means are provided for metering the organic material and for dividing the material into particles of substantially uniform size.

As here embodied, the feed means is illustrated in more detail in FIG. 7 and includes a conduit 52 for passing the organic material from feed hopper l to milling and heating or mill dehydrator 3 (FIG. 1 A rotatable shaft 53 is located within the conduit, and a primary feed screw 52' is mounted on one end of the shaft for moving the organic material through the conduit as the shaft rotates. A screen 53' is also mounted on the shaft and downstream from primary feed screw 52'. The screen is used to separate liquids from solids in the organic material and is an open-ended cylindrical member 53 coaxially positioned with respect to shaft S3 and having a plurality of apertures 54 spaced about the cylindrical member.

A steam inlet 56 is located in conduit 52 adjacent to the screen and a drain outlet 55 is located in the conduit adjacent to the screen so that liquids from the organic material drain through the screen and out the drain outlet as steam enters via the steam inlet to reverse flush and clean the screen.

A secondary feed screw 58 is also mounted on shaft 53 and downstream from'screen 53' for moving the organic material along within the conduit and into milling and heating means 3. A feed motor 18 and speed controller 20 are coupled to shaft 53 for controlling rotation of the shaft about its axis. In addition, knives (not shown) or other conventional means for cutting the organic material as it passes through feed means 2 are provided and means for pressing the material (not shown) may also be provided.

In accordance with this invention, means are located for receiving organic material from feed means 2 and for simultaneously milling and heating the organic ma- 7 terial by applying centrifugal forces and substantially equal and opposed aerodynamic forces to the material until the desired powder, meal, or flakes are produced and the aerodynamic forces becomegreater than the centrifugal forces. As here embodied, the milling and heating means'include mill dehydrator 3 having furnace 4 positioned adjacent thereto for heating the interior of the mill dehydrator.

As illustrated in FIGS. 2 and 3, the mill dehydrator includes a generally cylindrical housing having a first inlet for receiving heated air from the furnace, a second inlet 13 for receiving organic material from feed means 2 and an outlet 14 for exhausting powder,

meal, or flakes from housing 10. A shaft 11 is positioned within the housing for rotation about its own axis, and the shaft is movable within bearings located at 11 and 11" within housing 10. means are also coupled to shaft 11 for rotating the shaft about its own axis and these rotating means include a mill motor 23 and a speed controller 21..A plurality of instruments 12, such as knives or hammers, are also fastened to shaft 11 for acting on organic material within housing 10 in the presence of heated air from the furnace to produce powder, meal, or flakes within the mill dehydrator.

The outlet 14 of the housing forms an annular opening around one end of shaft 11, and second inlet 13 is preferably located adjacent to the opposite and of the shaft. First inlet 15 is also positioned, as best illustratedin FIG. 3, to permit heated air to enter the interior of housing 10 radially with respect to shaft 11. This radial entry of the heated air is significant because the aerodynamic forces applied to the material within housing 10 are substantially equal and opposed to the centrifugal forces applied to the material by rotation of instruments 12 until the material is processed to the desired extent when the aerodynamic forces overcome the centrifugal forces and the material is exhausted from the mill dehydrator. This balancing of centrifugal forces and aerodynamic forces on the material within housing 10 is an important factor in the unique success of the apparatus and process of this invention.

The milling and heating means, as here embodied, further includes a furnace 4, as illustrated in FIG. 4. An inner housing 37 forms a combustion chamber 36 and an outer housing 39 is spaced from the inner housing to form an annular space 38 therebetween. Outer housing 39 has a plurality of apertures 41 therein and these apertures are adjacent one end of the outer housing and in fluid communication with annular space 38 and with ambient air for enabling air to pass through the ap ertures and into space 38. Burner means 19 are positioned at least partially within combustion chamber 36 and outlet means 35 are located in fluid communication with the combustion chamber and annular space 38 and with the interior of housing 10 of the mill dehydrator. a

Means for generating steam are also provided and include steam manifold 26 partially located within combustion chamber 36. A steam jacket 26 (FIG. 1) is also provided at least partially surrounding feed means 2, and conduit means 26" are provided to connect steam manifold 26 with the steam jacket so that the material within feed means'2 can be heated to the desired degree. A water level sensing switch 32 is connected across the inlet and outlet pipes of the steam manifold and this switch senses the water level in manifold 26 and opens or closes solenoid valve 33 on the inlet side of the manifold to maintain the required level of water in, the manifold.

Burner means 19 are located atone end of burner 4, and oulet means 35 are located at the opposite end of the burner. Fuel is mixed with air and is burned at a very high temperature with low velocity air within combustion chamber 36. This results in complete combustion of the fuel within the combustion chamber and prevents ignition of organic material in the mill dehydrator or contamination of the material by products of incomplete combustion. The high temperature products of combustion are then mixed with cooling air 40 entering through apertures 41 to provide the desired air temperature for passage through outlet means 35 and for entrance into the interior of housing 10.

The cooling air enters the furnace through ports or apertures 41 in outer housing 39 and travels the length of the outer housing inside annular space 38 to a set of ports 34 in inner housing 37. The cooling air 40 then enters into the area adjacent the end of combustion chamber 36 away from burner means 19 where it mixes with the hot products of combustion to form air having the desired temperature for entrance into-mill dehydrator 3.

The location of cold air ports 34 near outlet means 35 insures that cornbustionoccurs in a low-flow, lowvelocity area required for complete combustion. In addition, the combined flows of air after'combustion provide the high velocity air stream at outlet means 35 reinlet 15.

In accordance with the invention, means are provided in fluid communication with the milling and heating means for enabling the powder, meal, or flakes to i be withdrawn from the milling and heating means. As here embodied, the withdrawing means includes a main exhauster fan 5 and a main exhauster motor 24 coupled to main exhauster 5 through aspeed controller 22.

Means are also provided in fluid communication with the withdrawing means for separating the powder. meal, or flakes from any heated air and steam exiting therewith from the withdrawing means. As here embodied, the separating means include a first cyclone or separator 6 in fluid communication with main exhauster 5, a cooling fan 7 for introducing ambient air among the powder, meal or flakes, and a second cyclone or dust separator 8 from which the final product emerges at outlet 9.

In accordance with the invention, control means are also connected for sensing the temperature of air, steam, and the powder, meal, or flakes exiting from the withdrawing means or main exhauster and for controlling operation of feed means 2 and of furnace burner means 19. As here embodied, the control means include a temperature sensor or thermocouple 17 located at the outlet of main exhauster 5 for sensing the temperature of the material, air and steam passing that point.

A signal from sensor 17 is conducted to temperature control 16, which determines when feed motor 18 is to be energized and material fed into mill dehydrator 3 and when and to what extent burner means 19 will operate.

In accordance with one embodiment of this invention, the burner means, as illustrated in FIG. 5, comprises a source of fuel 44, a fuel pump 42 in fluid communication with the fuel source, a main fuel nozzle 45 in fluid communication with the fuel pump and located within combustion chamber of the furnace, a plurality of additional fuel nozzles 28 in fluid communication with the fuel pump and located within combustion chamber, and a plurality of fuel valves 29 in respective fluid communication with fuel pump 42 and with additional fuel nozzles 28.

Fuel valves 29 are also in operative relationship to be controlled by control elements 30 whereby the heating of air within the furnace is determined by sensing of the temperature of air, steam, and the powder, meal or flakes passing temperature sensor 17. A main fuel valve 27 is also located in fluid communication with fuel pump 42 and with main fuel nozzle 45 for controlling the amount of fuel supplied to the main fuel nozzle. However, the main fuel valve need not be controlled by temperature controller 16 or by any individual control element 30. Rather, the main fuel valve may remain on -at all times during operation of the apparatus. Of

course, main fuel valve 27 could be readily controlled by temperature control 16 or by any other desirable means, if desired.

Provisions are also made to compensate for changing atmospheric conditions by including a fuel pressure adjustment 43 in fluid communication with pump 42 in each of the embodiments of FIGS. 5 and 6. This permits the operator to increase the fuel pressure in cold weather to compensate for colder and more dense air or to decrease the fuel pressure in warm weather.

In accordance with another embodiment of this invention, as illustrated in FIG. 6, the burner means comprise a source of fuel 44, a fuel pump 42 in fluid communication with the fuel source, a fuel nozzle or nozzles47 in fluid communication with the fuel pump and located within combustion chamber of the furnace, and a plurality of fuel valves 48 in fluid communication with the fuel pump and in parallel fluid flow relationship with one another. Each of these fuel valves is in operative relationship to be controlled by control elements 30 whereby the heating of air within the furnace is controlled by sensing of the temperature of air, steam and the powder, meal or flakes passing temperature sensor 17. A restrictor 49 may also be located in fluid communication with fuel valve 48 and with fuel nozzles 47 to provide the desired fuel pressure to the nozzles under various operating conditions.

In operation of the process and apparatus of this invention, raw organic material is loaded into feed hopper 1 and is conveyed by gravity or other conventional means from the hopper into feed means 2. The material is then fed along a predetermined path within feed means 2 and the material is pressed, cut and broken up into substantially uniformly sized particles.

As best illustrated in FIG. 7, the raw material contains large quantities of free water, fats or oils, and it may be desirable to remove these before the material enters mill dehydrator 3. This removal is accomplished by self-cleaning rotating screen 53. The mixture of solids 50 and liquids 51 proceeds through conduit 52 and is metered by means of primary feed screws 52'. As the mixture of solids and liquids pass over rotating screen 53, liquids 51 pass through holes 54 and out through drain 55. Screen 53' rotates continuously with shaft 53, as controlled by feed motor 18. Thus, holes 54 in the screen are alternately positioned opposite drain 55 and opposite high pressure steam inlet 56 where steam 57 from manifold 26 reverse flushes holes 54 to clean them before they are again positioned in front of drain outlet 55. The steam pressure also helps to force liquid 51 out through drain outlet 55, and solids 50 continue past the rotating screen to be picked up by secondary feed screw 58. The secondary feed screw then meters the solids and continues to move them along through conduit 52 and into mill dehydrator 3 for further processmg The amount of material passing through feed means 2 is controlled by the metering action of the primary and secondary feed screws so that the rate at which the material is fed into mill dehydrator 3 can be controlled by adjusting the speed of feed motor 18. As the material passes through feed means 2, it is also heated by a steam jacket 26' (FIG. 1) and direct injection of steam may also be used to break down the fatty tissue in very oily materials for easier removal of the oil.

The substantially uniformly sized particles are then fed from secondary feed screw 58 through second inlet 13 and into housing 10. As the particles of material enter housing 10, they are struck by the rapidly rotating instruments 12, such as knives or hammers, and the particles are whirled around the inside of the housing. Because of the centrifugal force (F generated by this rotation, the particles are thrown against the inner portion of the housing where most of the momentum of the particles is dissipated. This momentum is dissipated in four primary ways. First, it is converted into destructive energy that fractures the raw particles and grinds them into increasingly smaller particles. In addition, the fracture of the raw particles separates the dry outer layers of material from the wet cores so that the dry material can be carried out of the mill by the air stream. Second, a portion of the momentum is converted into heat. Third, some particles rebound off the inner wall of housing 10 and back into the path of instruments 12 where the particles are again thrown against the housing wall. Fourth, the particles which have lost most of their momentum fall to the bottom of housing 10 where they are picked up by instruments 12 and again thrown against the inner wall of the housing.

The centrifugal force (F imparted to the particles of material within mill dehydrator 3 is proportional to the mass of the particles (M), the diameter (D) defined by instruments 12 (FIG. 3) and the square of the rotational speed (N) of the instruments. Thus, F, MDN.

As the rapidly rotating particles carried by the knives or hammers 12 pass hot air inlet 15, high velocity hot air impinges on each and every particle to produce an aerodynamic force (F,,) proportional to the square of the relative air velocity (V,,), the mass density of the air (P) and the area of the particle (A). Thus, F z PAW.

When the material particles pass hot air inlet 15, the centrifugal force and the aerodynamic force acting on each material particle are substantially equal and in opposition to each other. For each type of raw material processed, the machine and the mill dehydrator are designed and dimensioned so that these forces are approximately equal when acting upon raw material particles within the mill dehydrator. 9 Because the particles have been broken up in feed means 2 within a predetermined range of sizes, the particles within the mill dehydrator will not leave the interior of the mill dehydrator to enter hot air inlet 15. For any particle of roughly spherical or gobular shape, the volume and associated mass increase as d while the area only increases as d, where d equals the diameter of the particle. Thus, it is necessary to pre-process the raw material in feed means 2 into some predetermined size range where the difference in diameters between the largest and smallest particles, A d, is of a predetermined value. As a result, the difference between A a, proportional to the masses of the particles, and A d, proportional to the surface areas of the particles, is very small, and F and F, on each particle remain within the predetermined range necessary for balancing of these forces and for the apparatus of this invention to operate in an optimum manner.

As the rotating knives or hammers 12 carry the raw material particlespast hot air inlet 15, the centrifugal force and the aerodynamic force on each particle is substantially equal and the radial velocity of each particle with respect to shaft 11 is substantially zero. However, as the particles are continually whirled around within the mill dehydrator, the hot air dries them and causes them to become lighter. As the mass is reduced from loss of water, the centrifugal force (F,,) is also reduced. The aerodynamic force (F,,), however, remains substantially constant because it is dependent primarily upon the area of the particle which remains essentially constant. Finally, the aerodynamic force overcomes the centrifugal force and causes the dried particle to move radially inwardly toward shaft 11 where it is picked up by axially flowing heated air and moved out through annular opening 14.

A particularly unique feature of the apparatus and process of this invention is that a particle cannot exit from mill dehydrator 3 until it has reached the desired size and state of dryness. Depending upon the dimensions of the mill dehydrator and onthe material being processed, the aerodynamic forces on the particles will only overcome the centrifugal forces when the desired size and state of dryness of the particles is achieved.

In addition, the mill dehydrator is extremely compact in size, but because of the extremely high relative velocity between the heated air and the particles within the mill dehydrator, the particles are rapidly dried and milled to the desired size and state of dryness. The entire process for individual particles within the mill dehydrator of this invention takes only seconds as com pared to hours required in many prior art devices.

Thus, the material is fed from feed means 2 into mill dehydrator 3 where centrifugal forces and substantially equal and opposed aerodynamic forces are applied to the material particles until the desired powder, meal or flakes are produced. The heated air is directed into mill dehydrator 3 in a radial direction with respect to shaft 11 and through inlet 15, which may be variable in area by means of a damper or other means to further control the amount of hot air introduced into the mill dehydrator. When the powder, meal or flakes have reached the desired size and consistency, they are withdrawn from the mill dehydrator through outlet 14 as a result of the aerodynamic forces overcoming the centrifugal forces.

The dry powdered product then passes throughmain exhauster 5 and into first cyclone or dust separator 6 where the product meal or powder is separated from any hot air and steam. The. dry meal then drops to the bottom of the first cyclone to the inlet of cooling fan 7 where the temperature of the product is reduced by mixing it with ambient air to prevent oxidation. The cooled product is then blown into second cyclone or dust separator 8 where the finished product is separated from air and steam and exits at cyclone exit 9.

Temperature control system 16 is conventional, and it senses the temperature of the air and product at the main exhauster outlet adjacent to temperature sensor or thermocouple 17. The control 16 starts or stops feed motor 18 at a predetermined temperature to prevent overloading of mill dehydrator 3. It also controls the rate of flow of fuel into the burner nozzles in response to the sensed temperature at the outlet of the main exhauster. The pressure of the fuel supply to the burner nozzles is controlled by fuel pump 42 and is adjustable to compensate for changes in weather or differences in raw material being processed. Manually or automatically operated speed controllers 20, 21, and 22 at feed motor 18, mill motor 23, and mainexhauster motor 24, respectively, also compensate for changes in weather or raw material.

The invention in its broader aspects is not limited to the specific details shown and described and departures may be made from such details without departing from the principles of the invention and without sacrificing its chief advantages.

What is claimed is:

1. Apparatus for processing raw organic material into clean sterilized powder, meal, or flakes, comprising:

feed means for feeding the organic material;

milling means located to receive organic material from the feed means and for simultaneously grinding and heating the organic material, said milling means comprising a housing, a plurality of grinding instruments rotatably mounted. about an axis within the housing for grinding said material, a feed inlet at one end of the housing for feeding the organic material into said housing, an air inlet intermediate the ends of the housing for feeding heated air into the housing in a direction substantially radial to the axis of rotation of the instruments, the centrifugal force imparted to the material by the rotating instruments being substantially counterbalanced by the opposed aerodynamic forces applied to the material by the heated air until the material has been dried and ground to the desired powder, meal, or flakes whereby the aerodynamic forces overcome the centrifugal forces and keep the ground material adjacent the axis of the housing, and an outlet located axially of and at the end of the housing opposite said feed inlet;

means in fluid communication with the outlet of the housing for withdrawing the powder, meal, or flakes from the milling means; and

means in fluid communication with the withdrawing means for separating the powder, meal, or flakes from the heated air exiting from the withdrawing means.

2. The apparatus of claim 1, wherein the feed inlet feeds the organic material into the housing in a direction substantially perpendicular to the axis of rotation of the instruments.

3. The apparatus of claim 2, wherein the feed inlet feeds the material into the housing in a direction substantially tengential to the path of rotation of the rotating instruments.

4. The apparatus of claim 2, wherein said grinding instruments extend along said axis from one end to the other of the housing.

5. The apparatus of claim 1, including a shaft positioned within the housing for rotation about said axis and means coupled to the shaft for rotating the shaft, the plurality of grinding instruments being fastened to and rotated by said shaft for acting upon the organic material within the housing in the presence of the heated air.

6. The apparatus of claim 1, wherein said outlet of said housing comprises means forming an annular opening of less diameter than the path of rotation of the instruments so that only the material ground to the desired powder, meal, or flakes and lying adjacent the axis will be exhausted from the housing.

7. The apparatus of claim 1, wherein the air inlet is a slot extending substantially from one end to the other end of the housing.

8. The apparatus of claim 7, wherein the grinding instruments extend along said axis from one end to the other end of the housing.

9. The apparatus of claim 7, wherein the air inlet slot is located a distance around the path of rotation of the instruments from the feed inlet.

10. The apparatus as in claim 1, wherein said milling means includes:

a furnace for heating air and in fluid communication with said milling means for enabling heated air to pass into said milling means to heat organic material within the milling means.

ll. The apparatus as in claim 10, further including:

control means connected for sensing the temperature of air,

and said powder, meal or flakes exiting from said withdrawing means and for controlling operation of said feed means and said furnace.

12. A process for converting raw organic material into clean sterilized powder, meal, or flakes comprising the steps of:

introducing the material into one end of a mill dehydrator;

whirling the material about a predetermined axis within the mill dehydrator to apply centrifugal force to the material; simultaneously with the application of the centrifugal force heating the material by directing heated air into the mill dehydrator in a substantially radial direction with respect to said axis and in an amount sufficient to provide opposed aerodynamic force to the material substantially equal to said centrifugal force so that when the finished powder, meal, or flakes is produced, the aerodynamic force will exceed the centrifugal force and direct the finished material toward the axis of the mill dehydrator;

withdrawing the powder, meal, or flakes and heated air from the mill dehydrator opposite the end where the material is introduced and in an axial direction; and

separating the withdrawn powder, meal, or flakes from the heated air.

13. The process of claim 12, wherein the organic material is introduced into the mill dehydrator in a substantially tangential direction with respect to the path of rotation of the whirling material.

14. The process of claim 13, wherein the heated air is radially directed into the mill dehydrator from substantially one end to the other end of the mill dehydrator and is located around the path of rotation of the whirling material from where the material is tangentially introduced. 

2. The apparatus of claim 1, wherein the feed inlet feeds the organic material into the housing in a direction substantially perpendicular to the axis of rotation of the instruments.
 3. The apparatus of claim 2, wherein the feed inlet feeds the material into the housing in a direction substantially tengential to the path of rotation of the rotating instruments.
 4. The apparatus of claim 2, wherein said grinding instruments extend along said axis from one end to the other of the housing.
 5. The apparatus of claim 1, including a shaft positioned within the housing for rotation about said axis and means coupled to the shaft for rotating the shaft, the plurality of grinding instruments being fastened to and rotated by said shaft for acting upon the organic material within the housing in the presence of the heated air.
 6. The apparatus of claim 1, wherein said outlet of said housing comprises means forming an annular opening of less diameter than the path of rotation of the instruments so that only the material ground to the desired powder, meal, or flakes and lying adjacent the axis will be exhausted from the housing.
 7. The apparatus of claim 1, wherein the air inlet is a slot extending substantially from one end to the other end of the housing.
 8. The apparatus of claim 7, wherein the grinding instruments extend along said axis from one end to the other end of the housing.
 9. The apparatus of claim 7, wherein the air inlet slot is located a distance around the path of rotation of the instruments from the feed inlet.
 10. The apparatus as in claim 1, wherein said milling means includes: a furnace for heating air and in fluid communication with said milling means for enabling heated air to pass into said milling means to heat organic material within the milling means.
 11. The apparatus as in claim 10, further including: control means connected for sensing the temperature of air, and said powder, meal or flakes exiting from said withdrawing means and for controlling operation of said feed means and said furnace.
 12. A process for converting raw organic material into clean sterilized powder, meal, or flakes comprising the steps of: introducing the material into one end of a mill dehydrator; whirling the material about a predetermined axis within the mill dehydrator to apply centrifugal force to the material; simultaneously with the application of the centrifugal force heating the material by directing heated air into the mill dehydrator in a substantially radial direction with respect to said axis and in an amount sufficient to provide opposed aerodynamic force to the material substantially equal to said centrifugal force so that when the finished powder, meal, or flakes is produced, the aerodynamic force will exceed the centrifugal force and direct the finished material toward the axis of the mill dehydrator; withdrawing the powder, meal, or flakes and heated air from the mill dehydrator opposite the end where the material is introduced and in an axial direction; and separating the withdrawn powder, meal, or flakes from the heated air.
 13. The process of claim 12, wherein the organic material is introduced into the mill dehydrator in a substantially tangential direction with respect to the path of rotation of the whirling material.
 14. The process of claim 13, wherein the heated air is radially directed into the mill dehydrator from substantially one end to the other end of the mill dehydrator and is located around the path of rotation of the whirling material from where the material is tangentially introduced. 